| OBJECTIVE:The aim of this study was to evaluate the effect of saliva contamination and de-contamination(water spraying) on the bovine enamel micro-tensile bond strengths of four commercially available self-etching adhesives.METHODS:Forty extracted non-carious bovine incisors were used to measure the enamel micro-tensile bond strength(μTBS).Labial enamel surfaces were grounded serially with 300-,600- and 1200-grit SiC paper under water cooling.Four commercially available self-etching adhesives and the corresponding composite resins from the same manufacturer((Clearfil SE Bond+Clearfil AP-X(SE,Kuraray Co., Tokyo,Japan),XenoⅢ+CeramⅩ(Densply,Konstanz,Germany),Frog+Ice(SDI, Southern Dental Industries,Australia),FL BONDⅡ+BeautifilⅡ(FL,Shofu Inc, Tokyo,Japan) were strictly applied according to the manufacturer's instructions with the exception of the saliva contamination groups.The enamel surfaces were treated as following conditions:Group A(control):non-contamination,Group B:saliva contamination before priming,Group C:saliva contamination after priming,Group D: water spraying of the saliva-contaminated enamel surfaces,Group E:water spraying of the adhesive-pretreated enamel surface contaminated with saliva.After 24 h water storage at room temperature,all the specimens were cut into about 1x1x8 mm with an Isomet low-speed saw(Isomer 1000,Buehler,Lake Bluff,IL,USA),and then micro-tensile bond tests were performed with a micro tensile tester(Bisco Co.USA). Enamel surface was analyzed with AFM(Atomic Force Microscopy) before/after the enamel surface was contaminated with saliva,and after the saliva-contaminated enamel surface was water-sprayed.Data were analyzed using one-way ANOVA,factorial design ANOVA and post hoc Tukey's HSD multiple comparisons. RESULTS:Comparison of the four adhesives in the control group(A) indicated that XenoⅢrevealed significantly higherμTBS than FL-BondⅡ(P＜0.01),however,no significant difference of theμTBS was found among the adhesives Clearfil SE Bond,XenoⅢand Frog(P＞0.05).Saliva contamination significantly reduced theμTBS of all the adhesives involved in this study(P＜0.001).However,the de-contamination procedures (water-spraying) could not restore theμTBS to their original level(P＜0.05),except for Clearfil SE Bond.TheμTBS obtained on the enamel surface that has been contaminated with saliva before adhesive application(Group B) could be significantly improved by thorough water-spaying before placement of the adhesive(Group D)(P＜0.05).AFM revealed some residual protein dots after the saliva-contaminated enamel surface was water-sprayed.Conclusions1.The hydrophilic self-etching adhesives are negatively influenced by saliva contamination.Proper isolation should be performed before and during the application of the adhesives and the placement of resin composite.2.Salivary protein on the enamel surface could not be removed by water-rinsing,and would interfere with the obtainable bond strength.The chemical bonding efficacy of some functional monomers such as MDP is promising to deal with saliva contamination. |
